The background patterns of space could help us focus on quantum problems.NASA / ESA / Hubble Heritage Team

The question of whether quantum mechanics is correct could soon be settled by observing the sky  and there are already tantalizing hints that the theory could be wrong.

Antony Valentini, a physicist at Imperial College, London, wanted to devise a test that could separate quantum mechanics from one of its closest rivals  a theory called bohmian mechanics. Despite being one of the most successful theories of physics, quantum mechanics creates several paradoxes that still make some physicists uncomfortable, says Valentini.

For instance, quantum theory uses probability to describe the properties of a particle. These properties obtain definitive values only when they are measured, which means that you cannot predict a particle's position or momentum, for instance, with certainty.

These premises troubled Albert Einstein. He believed that particles contain extra properties  or 'hidden variables'  that determine their behaviour completely. If only we knew what these hidden variables were, we could predict the fate of particles and the outcome of measurements with certainty. Bohmian mechanics is one of a suite of 'hidden variables' theories  many now discredited  formulated to tackle this problem.

Neck and neck

So far its been impossible to pick apart quantum mechanics from bohmian mechanics  both predict the same outcomes for experiments with quantum particles in the lab.

But Valentini thinks that the stalemate could be broken by analysing the cosmic microwave background  the relic radiation left behind after the Big Bang. The cosmic microwave background contains hot and cold temperature spots that were generated by quantum fluctuations in the early Universe and then amplified when the Universe expanded.

Using the principles of quantum mechanics, cosmologists have calculated how these spots should be distributed.

Its far too early to say that this is definite evidence of a breakdown in quantum mechanics  but it is a possibility. Antony Valentini Imperial College, London

However, Valentinis calculations show that the hidden-variables theory might give a different answer. Any violation of quantum mechanics in the early Universe would have a knock-on effect that we could see today, says Valentini.

Almost all measurements of the cosmic microwave background seem to fit well with the predictions of quantum mechanics, says Valentini. But intriguingly, a distortion that fits one of Valentinis proposed signatures for a failure of quantum mechanics was recently detected by Amit Yadav and Ben Wandelt at the University of Illinois at Urbana-Champaign (see 'Deflating inflation?'). That result has yet to be confirmed by independent analyses, but it is tantalizing, Valentini adds.

Its far too early to say that this is definite evidence of a breakdown in quantum mechanics  but it is a possibility, he says.

Cosmic predictions

Hiranya Peiris, an expert on the cosmic microwave background at the University of Cambridge, UK, is impressed by the new work. This is a pretty cool new idea, she says. Nobody has ever thought of using the cosmic microwave background to look into really fundamental quantum questions  cosmologists just assume that quantum mechanics is correct, she says.

But Peiris adds that Valentini must now come up with more detailed predictions about the types of distortion that will arise in the cosmic microwave background to convince cosmologists that they are really caused by a breakdown of quantum mechanics. He has thrown some really exciting ideas out there, but now he needs to do the nitty-gritty calculations, she says.

Vlatko Vedral, a quantum physicist at the University of Leeds, UK, agrees that the cosmic microwave background will be a useful way to test quantum mechanics. But he adds that even if quantum mechanics is shown to break down in the early Universe, that doesnt necessarily mean that the hidden-variables theory is correct.

"His beloved Son [Jesus Christ]...is the image of the invisible God...by Him all things were created, both in the heavens and on earth, visible and invisible...all things have been created through Him and for Him. He is before all things, and in Him all things hold together."

Colossians 1

4
posted on 05/18/2008 11:10:49 PM PDT
by EternalVigilance
("I have a clear record of working with Dems. I will appoint Dems to my administration." -Sen McCain)

As I understand quantum electrodynamics, the hidden-variables explanation has already been shown to be incorrect. A quantum physicist would know that, so I’m thinking that this article may just be nonsense - maybe somebody who really understands this can explain this to me.

Einstein said that it doesn’t make sense that God would play dice with the universe. However, quantum theory has been proven to be valid, despite the fact that it doesn’t make intuitive sense to us.

At the quantum level, given a set of exact starting conditions we can’t say what will happen next - but we do know that if the exact same starting conditions are repeated a large number of times the set of results can be predicted with great accuracy.

So, that’s the same as if God is throwing dice or flipping a coin to determine what happens next at the quantum level.

A fool and a liar. He was begged by his colleagues during his American tour in 1939 to not remain in Nazi Germany, but immigrate to the U.S. or any other Western democracy, just don't work for Hitler because it was discovered that year that atoms could split and a terrible bomb could theoretically be possible. But Heisenberg was another patriotic German still traumatized after WWI, and he stayed in his Fatherland while all his Jewish friends and colleagues were fired from German universities and had to seek employment -and safety - in other countries.

He and his team of German physicists attempted to make an atomic pile, but really got no where. Enrico Fermi, whose wife was Jewish and their two children were therefore half Jewish immigrated to the U.S. and Fermi created the first fission reactor underneath Stagg Stadium in Chicago in 1942. Heisenberg's team never got anywhere close to what Fermi's team accomplished that day in Chicago, but their arrogance was such that they never dreamed that atomic bombs could be created in the U.S.

After Germany surrendered in May, 1945, Heisenberg and the other leading German physicists were rounded up and sent to England to a very well bugged residence, and their conversations were all recorded. It was Heisenberg's opinion that Americans were very good at making things like cars, but they weren't up to making such as advanced things like A bombs. In fact, the German physicists were confident that they had a lot to teach the Allies about their research, and that could be a sort of a bargaining chip for them.

Their world crashed in around them when the news came that the U.S. had A bombed Japan twice. The German scientists tried to believe those weren't A bombs because it made them look so inferior. Finally Carl Friedrich von Weizecker (a German diplomat's son) began suggesting that they could have made A bombs for Germany but they were too moral to do so. Any transcript of the tape recordings made of the German physicists held in England show that the Germans - led by Heisenberg - just weren't up to it. But they had their alibi and they all stuck with it trying to cling to the moral high ground until their deaths.

It’s early yet, but if this thread holds to form, the physics folks in the Freeper family will be out in full force and I’ll again be reading posts I don’t understand after the second word. It’s very impressive when you guys do that. There are boatloads of knowledge floating around this place that are ready to dock and unload on any subject.

I just checked in on Schroedinger’s cat and he’s alive with excitement about these new theories but he’s dead certain they aren’t complete. “Could just be another scientist Hawking his Bohring pet theory” he told me politely.

“At the quantum level, given a set of exact starting conditions we cant say what will happen next - but we do know that if the exact same starting conditions are repeated a large number of times the set of results can be predicted with great accuracy.

So, thats the same as if God is throwing dice or flipping a coin to determine what happens next at the quantum level.”

The “dice” or “coin flip” analogy is probably correct, though most physicists do not think about it. The behavior of dice and coins is not random, but quite distinctly physically determined. The presumed “randomness” has entirely to do with our ignorance of what is going to happen.

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